Microsoft's Windows Phone may not be popular, but it is persistent even in 2015

Microsoft's summer of 2015 is nothing too exciting considering the software company is "in between" OS releases and trying just to maintain their sliver of the mobile market. Still, if there is one bit of silver lining, it is that their Lumia 640 appears to be filling in the gaps until later this fall.

The latest numbers from AdDuplex reflect a 2.4 percent increase in the Lumia 640's U.S. Windows Phone market share over last month. In the States, this brings the Lumia 640 to a surprising 11.2 percent of all active Windows Phones. Considering that IDC's latest numbers show that Microsoft is still hanging on to their low 2.6 percent the overall smartphone market (including iOS, Android, and BlackBerry), it is safe to say the Lumia 640 is the phone is responsible for that.